This invention relates to the construction of concrete slabs, and in particular to a support structure that is rapidly and efficiently put in place, and rapidly and efficiently removed in condition for re-use.
Concrete slab construction is, of course, a routine method for horizontally covering open areas between columns and girders affixed to the walls of buildings, parking garages, and so on. A typical procedure for installing these concrete "floors" is to first place shoring members across the columns and girders, with shoring support posts rising from the ground or the deck below to the concrete floor being installed. Corrugated decking is then placed on the surface of the shoring, with the edges of the decking overlapping flange edges on the permanent building wall, girders and columns. Post-tensioning steel cables are then placed over the decking to add strength to the resultant structure. Wet concrete is then poured over the corrugated decks. Alternately the post tensioning cables can be placed in the wet concrete as opposed to prior to the pouring. The concrete is then allowed to harden over a period of time. The supporting members can be so designed as to be removable after the concrete has hardened, simplifying concrete slab maintenance, and permitting re-use of the support structure on additional floors.
Various methods have been proposed for removable concrete slab support systems as is evident from the following examples. Keppler, in U.S. Pat. No. 1,707,226, discloses a supporting structure for concrete construction. This invention teaches a height adjustable shore 12 (centering post) cooperating with flanged 18 sheet metal members 16 (corrugated decking) connecting to height adjustable recesses 21 in soffit chairs. The invention notes (col. 2, lines 01-109), "a!fter the concrete has been sufficiently set, the shoring may be removed and the ledgers taken down, whereby the centering forms with the soffit chairs may be removed and permanent shoring mounted in place to engage the soffit plates or boards for continuing to support the concrete until it is firmly set with full strength". Lutz, in U.S. Pat. No. 3,059,738, discloses a removable concrete slab support wherein a portion of the support may be removed for the sake of economy prior to the concrete being fully set. An intermediate support 2 upheld by a prop 3 holds concrete slab supporting girders 1 and end supports 4 in place during the initial phase of setting wet concrete. Cornell, in U.S. Pat. No. 4,856,252, discloses a joist hanger 10 for removably securing a joist 38 during concrete slab construction. The joist hanger 10 has a box like metal configuration for securing the end of a suitable joist in the hanger. The joist hanger 10 has an extension section 18 for overlapping the top surface of a wall or girder 52, with a roll bar 22 acting as a pivot located a spaced distance below the extension section. After a concrete slab 34 is solidified on as suitable support 36, a sharp blow to the hanger causes it to pivot on roll bar 22, thereby releasing the hanger 10, joist, and support form the hardened concrete slab.
While these devices and methods disclose useful details for installation and removal of concrete slab support systems, they do not envision the efficiencies and conveniences inherent in the present invention. As will be more fully discussed below, this invention discloses a removable structure and method for supporting wet concrete during concrete slab construction without making use of vertical posts or shoring members which have to be supported down through the floors below to the ground. Accurate set up of corrugated decks is quickly accomplished to accept wet concrete. After the concrete has hardened all support members are quickly removed, ready for re-use as required.
It is therefore a primary object of the invention to provide a removable structure for supporting concrete slab construction that can be quickly put in place prior to the pouring of wet concrete, and quickly removed in re-usable condition after the concrete has hardened.
A further object of the invention is to eliminate the necessity for using vertical posts or shoring members which would have to be supported down through the floors below to the ground.
Another object of the invention is to permit the pouring and forming of a number of levels of concrete slabs in any desirable sequence.
Still another object of the invention is to provide for the plane of the shoring to always be automatically in the plane of the floor being formed.
Yet another object of the invention is to provide for rapid and convenient adjustment of the thickness of the concrete slab being formed.
A further object of the invention is to eliminate the necessity for permanently affixing structural support members to each other.
An additional object of the invention is to provide for most efficient placement of steel tendons within the concrete if post tensioning reinforcement concrete slab production is employed.